The Dummy Talks (1943)

This mystery is set around a London music hall show, featuring a lot of well known music hall stars of the time, (playing themselves) like Jack (Blue Pencil) Warner doing his stage routine for the first time on film.... and impressionist Beryl Orde, Ivy Benson and her all ladies band, The Skating Avalons, Five Lai Founs, etc The show's ventriloquist act is murdered but we learn, there are a few characters that have a motive. The mystery of who killed him is investigated by a star struck fraud detective, Claude Hulbert, who is only there to hang around one of the female stage stars, whom he has a big crush on. This detective is rather clumsy and somewhat dim witted (which Claude Hulbert was known for playing at the time and is based on his own stage persona) but as he tries to find out who the murderer really is, he finds a number of possible suspects who all have something to hide, including a stranger who has been hanging around the back stage and is clearly acting suspiciously...as the film goes on, we find, the motive for the murder appears to be linked to a currency counterfeiting scheme that is linked to a mysterious Mr Harriman who has a box seat reserved for the show but has not taken his seat, while all this is going on back stage, the show must go on so we get to see the plot develop as the music hall acts perform their songs and routines on stage..... The murderer is finally revealed by the ventriloquist's 'dummy'......